This application generally relates to an oil supply system for a planetary gear system. More particularly, this application relates to an uninterruptible oil supply system for a planetary gear system.
Conventional planetary gear assemblies include a carrier housing supporting rotation of various gears. Each gear is supported on a journal shaft and supplied with lubricant through passages within the journal shaft. Lubricant is delivered to the journal shaft by a primary delivery system. A secondary delivery system is typically included to provide lubricant if the primary delivery system fails. Although, the secondary system will continue lubricant delivery to the journal shaft and thereby to the gears, there is inevitably a time delay between failure of the primary delivery system and reestablishment of lubricant flow provided by the secondary delivery system. During the time delay lubricant is not provided to the journal shaft. The absence of lubricant can have undesired affects, especially in high-speed applications such as those commonly used in aircraft drive train applications.
Lubricant delivered to the journal shaft generates a lubricant film between the journal shaft and the gear supported thereon. The lubricant film is necessary to prevent undesirable contact between the gear and the journal shaft. During the interim between failure of the primary lubricant delivery system and engagement of the secondary system it is possible that the lubricant film will dissipate due to the temporary absence of lubricant, thereby allowing contact between with the gear and the journal shaft. This undesirable touchdown of the gear can cause undesirable damage and premature wear.
The carrier housing body typically experiences some degree of twisting caused by transmission of torque to the gears supported thereon, which can result in undesirable bearing misalignment. Such misalignment can cause premature wear or damage to the journal shaft. Typically, the effect of torsional twisting of the carrier housing is minimized by the application of a torque frame system. The torque frame provides support for the carrier housing and transmits torque through a shaft to an engine system. However, such a system does not provide an accommodation for the interim time period between failure of a primary lubricant system and engagement of the secondary lubricant system.
Accordingly it is desirable to design and develop a lubricant supply system that provides effective and reliable lubricant delivery in the interval between failure of the primary system and reestablishment of lubricant flow by a secondary system.